# Mars Exploration – HackerRank Solution

In this post, we will solve Mars Exploration HackerRank Solution. This problem (Mars Exploration) is a part of HackerRank Problem Solving series.

A space explorer’s ship crashed on Mars! They send a series ofÂ `SOS`Â messages to Earth for help.

Letters in some of theÂ `SOS`Â messages are altered by cosmic radiation during transmission. Given the signal received by Earth as a string,Â s, determine how many letters of theÂ `SOS`Â message have been changed by radiation.

Example

s = ‘SOSTOT’

The original message was `SOSSOS`. Two of the message’s characters were changed in transit.

Function Description

Complete the marsExploration function in the editor below.

marsExploration has the following parameter(s):

• string s: the string as received on Earth

Returns

• int:Â the number of letters changed during transmission

## Input Format

There is one line of input: a single string,Â s.

## Constraints

• 1 <= length of s <= 99
• length of s modulo 3 = 0
• sÂ will contain only uppercase English letters, ascii[A-Z].

Sample Input 0

``SOSSPSSQSSOR``

Sample Output 0

``3``

Explanation 0

sÂ =Â SOSSPSSQSSOR, and signal lengthÂ |s| = 12. They sentÂ 4Â `SOS`Â messages (i.e.:Â 12/3 = 4).

``````Expected signal: SOSSOSSOSSOS
Recieved signal: SOSSPSSQSSOR
Difference:          X  X   X``````

Sample Input 1

``SOSSOT``

Sample Output 1

``1``

Explanation 1

sÂ =Â SOSSOT, and signal lengthÂ |s| = 6. They sentÂ 2Â `SOS`Â messages (i.e.:Â 6/3 = 2).

``````Expected Signal: SOSSOS
Difference:           X``````

Sample Input 2

``SOSSOSSOS``

Sample Output 2

``0``

Explanation 2

Since no character is altered, return 0.

## Solution – Mars Exploration – HackerRank Solution

### C++

```#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;

int main(){
ios::sync_with_stdio(false);
string str;
cin >> str;
int ans = 0;
for( int i = 0; i < str.size(); i += 3 ){
if( str[i] != 'S' ) ans++;
if( str[i+1] != 'O' ) ans++;
if( str[i+2] != 'S' ) ans++;
}
cout << ans << '\n';
return 0;
}
```

### Python

```import sys

def marsExploration(s):
res = 0
for ind in range(0, len(s), 3):
if s[ind] != 'S':
res += 1
if s[ind+1] != 'O':
res += 1
if s[ind+2] != 'S':
res += 1

return res

if __name__ == "__main__":
s = input().strip()
result = marsExploration(s)
print(result)
```

### Java

```import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

static int marsExploration(String s) {
int l=s.length()/3;
int x=0;
int c=0;
while(x<s.length())
{
String t=s.substring(x,x+3);

if(t.charAt(0)!='S')
{
c++;
}
if(t.charAt(1)!='O')
{
c++;
}
if(t.charAt(2)!='S')
{
c++;
}
x=x+3;
}
return c;
// Complete this function
}

public static void main(String[] args) {
Scanner in = new Scanner(System.in);
String s = in.next();
int result = marsExploration(s);
System.out.println(result);
in.close();
}
}
```

Note: This problem (Mars Exploration) is generated by HackerRank but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.